A strategy to increase cooperation in the volunteer's dilemma: reducing vigilance improves alarm calls.

摘要: One of the most common examples cooperation in animal societies is giving alarm presence a predator. A reduction individual vigilance against predators when group size increases (the "group effect") one frequently reported relationships study behavior, and thought to be due relaxed selection, either because more individuals can detect predator easily "many eyes" effect) or risk attack diluted on "selfish herd" effect). I show that these hypotheses are not theoretically grounded: everybody relies someone else raise alarm, probability at least raises declines with size; therefore increasing does lead selection. Game theory shows, instead, (by reducing vigilance) induces give often. The effect, therefore, strategic behavior improve production public good. This shows how selfish benefit for group, suggests way solve social dilemmas absence relatedness repeated interactions.